Polyarylene sulfides are resins having properties suitable for engineering plastics, such as excellent heat resistance, barrier properties, chemical resistance, electrical insulating properties, moist-heat resistance, and flame resistance. In particular, polyphenylene sulfide resins can be molded by injection molding and extrusion molding into various molded parts such as films, sheets, and fibers and have been widely used in the fields of various electrical and electronic components, machine parts, automotive parts, and other parts requiring heat resistance and chemical resistance.
Polyphenylene sulfide resins, however, are inferior to other engineering plastics in shock resistance, toughness, and molding processability, and to improve these properties, combination with a different polymer has been attempted. Typical methods of the combination include blending a polyphenylene sulfide with any other different polymer to form a polymer alloy and chemically bonding with a different polymer to form a block copolymer. Of these, block copolymerization, as compared with other combination methods, enables the formation of uniform and fine phase-separated structures and has hitherto been extensively studied as a technique for modifying polyphenylene sulfides.